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WorkStudy
1Work Study Definition by ILO: ' Is a generic term for techniques, particularly ''method study and time study, which are used ' arranged for another operation, transportation, inspection, or storage. Transportation Change in location of object from one place to another Inspection Examination of object to check on quality or quantity achine, a person and several machines, or any combination of people and machines where delays are prevalent, the multiple activity chart provides a convenient technique for analyzing the combined activity. Very often the objectives of this type of analysis are to attain the maximum utilization of a machine, to attain the optimum person to machine relationship, or to bring about the best balance of crew activity. For this reason, the time factor is an important consideration and necessitates the use of a graphical representation involving time. Use of Videotape In the past, the experienced methods engineer found that one of the most important aids was the use of motion pictures. There are many situations in which it is difficult to observe all of the action taking place because of the high speed of activities or the complexity of the operation. Having observed slow-motion motion pictures, we are familiar with the fact that one can take motion pictures at high speed and then, by projecting them at normal speed, slow the action down. By the same token, we can take the pictures at slow speed and project them at what appears to be high speed. In using motion pictures, methods engineers may have had several objectives in mind. First and foremost, they may have wanted a permanent record of the work as it was being performed. Or they may have wished to use the film for analysis purposes, commonly referred to as “micromotion” or “memomotion” studies, discussed in some detail in sections that follow. Micromotion Study Micromotion study, which was originated by Frank B. Gilbreth, is one of the most exacting forms of work analysis available for job improvement. It is an analysis technique making use of motion pictures (or videotape) taken at a constant and known speed. The film becomes a permanent record of both the method being used and the time consumed in doing the work. Although micromotion study formerly made use of motion pictures, very few companies today are using them. As indicated earlier, videotape equipment has been developed so extensively that it has virtually supplanted the use of the motion picture camera. Further it is so cheap and easy to use that it makes the older approach archaic. Micromotion study provides a valuable technique for making minute analyses of those operations that are short in cycle, contain rapid movements, and involve high production over a long period of time. Thus it is very useful in analyzing operations such as the sewing of garments, assembly of small parts and similar activities. Memomotion Study Before leaving the general area of micromotion study, let us touch briefly on memomotion study. Memomotion study, which was originated by M.E. Mundel, is a special form of micromotion study in which the motion pictures or videotape are taken at slow speeds. Sixty and one hundred frames per minutes are most common. Memomotion study has been used to study the flow and handling of materials, crew activities, multiperson and machine relationships, stockroom activities, department store clerks, and a variety of other jobs. It is particularly valuable on long-cycle jobs or jobs involving many interrelationships. In addition to having all of the advantages of micromotion study, it can be used at relatively low film or tape cost (about 6% of the cost at normal camera speeds) and permits rapid visual review of long sequence of activities. Principles of Motion Economy Through the pioneer work of Gilbreth, Ralph M. Barnes and other investigators, certain rules for motion economy and efficiency have been developed. Some of the more important of these principles are the following: 1. The movements of the two hands should be balanced and the two hands should begin and end their motions simultaneously. 2. The hands should be doing productive work and should not be idle at the same time except during rest periods. 3. Motions of the hands should be made in opposite and symmetrical direction and at the same time. 4. The work should be arranged to permit it to be performed with an easy and natural rhythm. 5. Momentum and ballistic-type movements should be employed wherever possible in order to reduce muscular effort. 6. There should be a definite location for all tools and materials, and they should be located in front of and close to the worker. 7. Bins or other devices should be used to deliver the materials close to the point of use. 8. The workplace should be designed to ensure adequate illumination, proper workplace height, and provision for alternate standing and sitting by the operator. 9. Wherever possible, jigs, fixtures, or other mechanical devices should be used to relieve the hands of unnecessary work. 10. Tools should be prepositioned wherever possible in order to facilitate grasping them. 11. Object should be handled, and information recorded. Only once. Job Enlargement and Enrichment This has led to the contention of a number of social scientists that hobs need to be enlarged or enriched. Feedrick Herzberg, one proponent of job enrichment, feels that the purpose of job enrichment should be to eliminate the undesirable characteristics of highly repetitive, specialized work by enlarging it to include: 1. Greater variety of knowledge and skill 2. Giving a person a complete natural unit of work (module, division, area, etc.) 3. More complex utilization of the important cognitive and motor abilities possessed by the worker. 4. More freedom and responsibility in the performance of the tasks at hand. Among the principles that commonly are applied in job enrichment programs, the following are attended to by one large company. 1. Ensure that there is variety in the job content. 2. Include in the work situation an opportunity for the worker to grow and learn. 3. Provide an opportunity for each worker to have knowledge of the part that his or her job plays in the total manufacturing process required to produce the product. 4. Design the work so that it has meaning to the worker and provides pride in performance to the worker. 5. Ensure that the work is reasonably demanding and functionally inclusive. Provide for self-direction of the work and for the checking of quality of output. Value Analysis As a part of the approach to methods improvement, the methods engineer should question the impact of the design of the parts, the materials used, and the equipment used on the productivity of operations. That is, the methods engineer should be thoroughly familiar with value analysis, an activity that is closely both to the methods improvement programs and to purchasing and that is being used extensively in industry and the government. Value analysis is an objective study of every item of cost in every component part, subassembly, or piece of equipment. This includes a study of the design, the material, and the process in a continual search for other possible materials and new processes. Value analysis involves the evaluation of an items function and relates its effect to the end product. The purpose is to attempt to ensure that every element of cost contributes proportionately to the function of the item. Social and Economic Effects of method Study As pointed out at the beginning of this chapter, modern industry is constantly searching for better methods. When a business ceases to move forward, it will lost ground and may eventually fail. It is for this reason that the major companies have organized industrial engineering groups, work simplification and value analysis programs, suggestion systems, quality circles, and other methods of achieving reduced costs of manufacturing their products. One of the consequences of these programs has been increased mechanization, which, in turn, has led to the production of more and more goods per work hour. Among the long-range benefits derived from this increased output have been higher real wages, an improved standard of living, a shorter work week, and a reaction of the physical rigors of the job. --' '''Work Measurement or Time study Method Study – Systematic recording & critical examination of the way of doing a work as a mean for developing more effective methods & reducing costs. Work Measurement – Establishing the time required by a qualified worker to carry out a specified job at a defined level of performance Steps in Method Study - : Recording Techniques - : # Process Charts ## Outline Process chart (or operation process chart) ## Flow Process chart (Man type; Material type; Equipment type) ## Multiple activity chart ## Two handed process chart (or Left hand-Right hand chart) ## SIMO chart (Simultaneous Motion Cycle chart) # Diagrams ## Flow diagram ## String diagram ## Cyclegraph ## Chronocyclegraph # Models i) Outline Process Chart – Gives bird’s eye view of the process; considers only main operations and inspections ii) Flow Process Chart – Detailed version of operation process chart shows the "OTIDS" Operation (transforms or performs work that the customer may see as Value which is the product or service Function at a Cost); Transport/Move; Inspection/Check; Delay/Wait and Store/File. Recent "OTIDS" have adde anoth D being Decision to become "OTIDDS". The use of "Value Stream Maps" in "Lean" (John Krafcik a research student at MIT in late 1980's) are enhanced for each major step in the Value Stream by using the Flow Process Chart to provide more details on the value and non-value activities in the Stream. Value Analysis/Value Engineering and Process Failure Mode and Effect Analysis techniuques in the Automotive qualkity and technical specificvation (ISO TS16949:2002) and Boeing Aircraft Corporation Quality Tools Manaul all use Flow Process Charts Person type – Sequence of activities performed by worker Material type – Sequence of activities performed on material Equipment type – Sequence of activities performed by equipment ' iii) Multiple Activity chart – Activities of more than one man or machine are recorded on a common time scale' iv) Two handed Process chart – Activities performed by two hands of worker are recorded on a common time scale v) SIMO chart – Detailed version of two handed process chart (micromotion study) vi) Flow diagram – Shows the relative position of machines and equipments and marks the path followed by man and material vii) String diagram – similar to flow diagram except that path is traced by a continuous string or thread viii) Cycle graph – To study the path of movement of operators hands; A small electric bulb is attached to hand and photograph is taken by a still camera ix) Chronocycle graph – Similar to cycle graph except that along with path it also shows direction and speed of movement. This is done by interrupting the light source so that path appears as a series of dots. ' SIMO chart is Micromotion study whereas' cycle graph and chronocycle graph are Memo Motion Study Memo Motion study involves time-lapse photography ie a still camera takes pictures of the activity at regular intervals (1 to 5 sec) unlike micromotion study which involves making a continuous motion film Memo motion study is used for activities which are not required to be examined in fine detail but are still too fast to be recorded accurately by human eye. Therbligs – are the fundamental hand motions which are performed over and again in any manual work, eg Search, find, select, hold, grasp, use, assemble, dissemble, inspect, release ' -developed by Mr. Gilbreth (Therblig is his name spelled backward) -used in micromotion study' ;Work Measurement :Std. time for any job may be established by 3 methods: Time Study (stop watch) Short cycle ; Repetitive jobs ''' Work Sampling Long cycle ; Heterogeneous operations PMTS Short cycle ; Highly-repetitive jobs' '' Work sampling' '''Time study Synthetic time P.M.T.S. Analytical estimating Direct Indirect Work Measurement ' Work Sampling' In this a no. of observations are made over a period othat instant. The percent of observations recorded for a particular activity is a measure of the percentage of time during which that activity occurs. ' Work Sampling is used for activities of very long duration which cannot be measured with stopwatch. Eg to find out actual working time of an operator in one shift.' It is based on Statistical theory of sampling – ie adequate random samples of observations spread over a period of time can construct an accurate picture of the actual situation of system. No. of observations required for 95% confidence level and ±5% accuracy (ie we are sure that 95% of the time the average value will not be having error more than 5% of the true value. ' N = 4p(100-p) (p = percent of occurance)' '--------------- (A = Accuracy required)' ' A2 ' StopWatch TimeStudy ' Why do we break down the activity to be studied into elements?(why not measure time straightly)' To provide a detailed work specification To separate value adding & non-value adding activities To select best method by comparing work elements of different methods Stopwatch – one revolution = 1 minute (1 deciminute = 1/100th of minute) Normal time = Observed time * rating factor Standard time = Normal time + allowances Rating – Comparing the pace rate or performance of a worker against standard performance level to take into account different operators’ performance level ' Rating techniques-''' '''Speed- Worker’s speed/speed expected However assigning a rating factor and allowances are largely subjective in nature and depends on personal judgment of timestudy engineer Allowances- it is the additional time provided over and above normal time to take into account time for relaxation, attending personal needs * Rest and personal allowances (to overcome fatigue incurred during working) * Interference allowances (to take into account m/c stoppages etc) * Special allowances (for activities which are generally not a part of work cycle) :In this we build up the total time for a job by summing up the times for different elements :Particularly useful for operations which are still in the planning phase and have not yet started (helpful in planning and scheduling) * Synthesis * PMTS (Predetermined Motion Time System) * Analytical estimating ;Synthesis :Element time values are taken from a catalogue of elements time built from timestudies done in the past PMTS also make use of previously collected data but it deals with basic human motions (or therbligs) of duration 0.1 seconds or less. Whereas in synthesis duration may be 3-4 seconds Analytical estimating is used when past time data is not available and estimator has to rely on his past experience. ' PMTS''' * '''For short cycle & highly repetitive jobs * Uses video film (micromotion study) * More accurate than stopwatch timestudies * No rating factor required but allowances need to be added * But can deal with only manual motions of the operation Method Time Measurement Work Factor Systems 1 TMU = 0.0006 minutes (TMU = Time Measurement Unit) 1 wink = 0.0005 minutes (used in SIMO chart/micromotion study) ' Analytical Estimating' For long and non-repetitive operations ; Least accurate (Machine elements – calculated from information of feed, speed, depth of cut etc) Comparison It is difficult to compare different work measurement techniques, as each technique has its own set of application ' Work sampling is used for long cycles eg amount of time actually spent working by a worker in a shift Time study is used for short repetitive cycles eg worker working on a assembly line ' [[Bold]] textPMTS is used for very short cycles which require a very detail analysis (micromotion study)' '''Time' study Work sampling Synthetic time P.M.T.S. Analytical Time Required MAX MIN Accuracy MAX MIN ' TIME & MOTION STUDY : A NEW PARADIGM' In theory there is no difference between theory and practice, ' In practice there is ……. ' I realized it by myself when I undertook a project on time & motion study during my summer internship. On paper it looks very easy to do timestudy with a stopwatch. But when you actually do it you realize the practical difficulties associated with the traditional method. stung ''' '''That’s why I picked up the cause in my final year project and developed a software which automates the process of time & motion study. Details about it can be seen at the following URL -: http://web.archive.org/20040901135623/in.geocities.com/time_motion_study http://www.professays.com/faq/ Please go through it; its worth a watch…… ---- Home About_IE IE_1 Quality WorkStudy New_Tech Manufacturing Contribute Contact Category:Video Work Study: Using Videos to do a total Work Study which includes Time Study, Method Study, Value Analysis, Delay Analysis & Ergonomic Assessments. For Details refer www.workstudy.in